1. Technical Field
The present disclosure relates to a control system of an internal combustion engine.
2. Description of Related Art
An internal combustion engine including direct injection valves and port injection valves is known. In the internal combustion engine, fuel pumped up by a low-pressure pump is supplied to the port injection valves via a low-pressure fuel passage, and the fuel further pressurized by a high-pressure pump is supplied to the direct injection valves via a high-pressure fuel passage. In this arrangement, a fuel sensor that detects the fuel pressure in the low-pressure fuel passage may be provided. Detection values of the fuel pressure sensor may be used for control of various controlled objects, such as the amounts of fuel injected from the port injection valves.
In the above-described arrangement, pulsation of the fuel pressure may occur in the low-pressure fuel passage, mainly due to driving of the high-pressure pump. If the fuel injection amounts of the port injection valves are controlled based on detection values of the fuel pressure sensor during occurrence of the pulsation, the fuel injection amounts may not be appropriately controlled, for the reason as follows. A certain period is required from the time when a detection value of the fuel pressure sensor is obtained, to the time when port injection is started based on the detection value. Therefore, if the pulsation is generated, the fuel pressure may vary largely during a period from the time when the detection value is obtained, to the time when port injection is started, and the obtained detection value and the actual fuel pressure value during port injection may be largely different from each other.
Thus, according to a technology described in Japanese Patent Application Publication No. 2012-237274 (JP 2012-237274 A), during occurrence of pulsation, the fuel injection amounts of the port injection valves are controlled, based on a map in which a correction value of the port injection amount is specified in advance for each rotational speed of the internal combustion engine, without using the actual fuel pressure values.